G4003G Repl apron gear

[epanzella]

The gear sticking out the back of my apron the meshes with the drive rack is chowed. I just got the replacement and it's an 11T gear on an integral polished shaft with no holes in it despite that the manual shows a roll pin going thru it. Grizzly Tech says they didn't put the hole in the shaft because it's more accurate to drill it in place with a hand drill. I'm not saying they're wrong but it's starting to smell a bit like low tide around here. I haven't taken the apron apart yet but on the parts diagram it looks like the roll pin is right along side a 25T gear which obviously has a much bigger diameter than the shaft. I don't know but I think it unlikely I'll be able to get a straight shot at drilling thru this ground shaft accurately with the unit in place. I would appreciate any opinions or advice from the group.
thx
Ed P

 

[Bob Korves]

The gear and shaft are usually drilled in place at the factory, often not even close to neatly on the center line. That is what it is, and there is no good way to drill the new gear to match the old hole, not even close. So you are better off noting or marking how far the gear fits onto the shaft and then drilling a new hole for the new gear with it in place on the shaft. Drill the hole to as much of a different clock position from the original as possible and still be able to assemble it OK. It is probably smart to drill the hole through one side of the gear before installing it on the shaft, and then drilling the rest of the way through with it installed properly on the shaft. The rotational position of gear to shaft does not matter. I prefer taper pins.

 

[darkzero]

Bob is correct, the holes for roll/shear pins for gears, leadscrews, handles, etc are often drilled at the factory with the part in place at the factory & often without much precision. In addition to what Bob said, if you have a mill, indicate the gear where you want to drill the hole & record the measurements. That way if you ever have to replace the gear again you'll have a good chance of drilling the same hole so you don't have to make more holes on the shaft & end up having to replace the shaft.

 

[epanzella]

Bob is correct, the holes for roll/shear pins for gears, leadscrews, handles, etc are often drilled at the factory with the part in place at the factory & often without much precision. In addition to what Bob said, if you have a mill, indicate the gear where you want to drill the hole & record the measurements. That way if you ever have to replace the gear again you'll have a good chance of drilling the same hole so you don't have to make more holes on the shaft & end up having to replace the shaft.

Thanks. The gear and the shaft are one piece and I don't have a mill. Any milling I do happens on the lathe with a milling attachment. Really sucks trying to locate holes. I had to TIG up scope mount holes and redrill them twice on a rifle I'm building because I suck at locating holes. My left hand is also trashed so holding stuff by hand is pain as well. But I'm alive and doing what I want, so there's that.

 

[darkzero]

Thanks. The gear and the shaft are one piece and I don't have a mill. Any milling I do happens on the lathe with a milling attachment. Really sucks trying to locate holes. I had to TIG up scope mount holes and redrill them twice on a rifle I'm building because I suck at locating holes. My left hand is also trashed so holding stuff by hand is pain as well. But I'm alive and doing what I want, so there's that.

Ah I see, I missed where you said the new gear came one piece with a new shaft. In that case it wouldn't really matter, just drill the hole for the pin with the new shaft in place. But if it was just a new gear & reusing the old shaft, with no mill you could make a thick sleeve to go over the shank of the gear, drill that & the gear, then save the sleeve for locating in the future.

 

[epanzella]

Just a followup. I finally got the new gear shaft and did the repair. The old gear shaft was bent. The factory tech said to assemble the gearbox and use a hand drill to drill the new pin in place. I have a missing finger on my left hand and the others don't work that great so doing something that takes three hands is not in the cards for me. My solution was to set up the old shaft in a fixture on my drill press with a pin in the chuck going thru the gear hub and old shaft to keep everything aligned. Then I drilled half way thru with the same set up using the old gear and new shaft. I put the roll pin half way thru to lock everything and drilled the rest of the hole from the other side. It lined up perfectly. I was shooting for .005 end play and hit it right on the nose. Thanks for the help, guys!

 

[epanzella]

Lathe is back together and all systems 100%. Again, thanks for the help everyone!

 

[darkzero]

Nice, great to hear!

No more drunk driving, er, I mean drunk lathing (I hate that word), I mean drunk machining.... just try not to crash anymore.

 

[westerner]

But I'm alive and doing what I want, so there's that.

And THAT is what it's all about! Well done!

 

[epanzella]

The gear and shaft are usually drilled in place at the factory, often not even close to neatly on the center line. That is what it is, and there is no good way to drill the new gear to match the old hole, not even close. So you are better off noting or marking how far the gear fits onto the shaft and then drilling a new hole for the new gear with it in place on the shaft. Drill the hole to as much of a different clock position from the original as possible and still be able to assemble it OK. It is probably smart to drill the hole through one side of the gear before installing it on the shaft, and then drilling the rest of the way through with it installed properly on the shaft. The rotational position of gear to shaft does not matter. I prefer taper pins.

Bob,
You were so right on factory holes not being perfectly centered. Although I got the holes lined up on the new gear shaft, I forgot to clock the orientation of the holes in the feed rod where it mates with the QCGB. When I put it together the roll pin went thru the feed rod and it's mating collar but it was a bit hard. After assembly I was turning the chuck by hand (I learned my lesson) to make sure there was no binding anywhere before putting power to it and I discovered the feed had a bit of a bind in it. I popped the pin out and rotated the rod 180 degrees and the roll pin went in easier. The bind was also gone. Thx for the hedzup!
Ed P